The primary focus of construction stormwater planning is to prevent sediment and other pollutants associated with construction activity from impacting soil, air, and water quality. Such impacts can increase project costs through regulatory and legal fines, and through repair of site damage and delays to project delivery.

The Stormwater Code (SMC 22.800-22.808) and associated Directors’ Rules have been revised to account for advances in urban stormwater runoff management practices. These regulations are in place to protect life, property, public health and the environment from the adverse impacts of urban stormwater runoff. Adverse impacts can include flooding, pollution, landslides and erosion.

Construction Stormwater and Erosion Control Plans (CSECP) are required to adequately and systematically identify and minimize project risk. The CSECP is needed to satisfy the construction stormwater pollution prevention requirements for all projects that require stormwater site plans.

All projects must apply appropriate best management practices (BMPs). Small projects (projects with less than 5,000 square feet of new plus replaced impervious surface) must implement the BMPs listed as conditions of the permit. It is the Permittee’s responsibility to evaluate the eighteen elements listed in SMC 22.805.020 to mitigate the project impacts. Large projects (projects with over 5,000 square feet of new plus replaced impervious surface) must have a CSECP, prepared by a licensed engineer, reviewed and approved as part of the Street Improvement plan set.